1. Field of the Invention
The present invention relates to respiratory circuits, in general, and, more particularly, to tracheostomy tubes comprising a composite outer cannula and a removable inner cannula.
2. Prior Art Statement
Tracheostomy tubes are well-known in the art. It is also well-known that a two part tracheostomy tube is used so that if the tracheostomy should be occluded by mucous or phlegm, the tracheostomy tube airway can be cleaned by removing the inner cannula, see U.S. Pat. No. 4,817,598, to D. LaBombard, for example.
In the past, the tracheostomy tube has been made of a relatively rigid plastic material such as ABS plastic or the like. These tubes are made according to ASTM or ISO standards which are well-known in the industry. The existing tracheostomy tubes comprise a bent or arcuate tube with a 15 millimeter (or similar) connection at one end which is connected to a breathing circuit or the like. These tubes include flanges at the proximal end thereof for attachment to a neck strap or the like to fasten the tracheostomy tube to the patient.
An inflatable cuff adjacent the distal end of the tube is used to effectively anchor the tracheostomy tube in the patient once the tube has been inserted. That is, the cuff is inflated and prevents removal of the tube from the tracheostomy. (It should be noted that pediatric tracheostomy tubes may not include the cuff for several reasons, notably the size of the patient and the patient's throat.)
The known tracheostomy tubes have several disadvantages. Because of the rigidity of the tube and the hardness of the material, trauma to the patient is frequently inflicted when the tube is inserted into the trachea. In like fashion, the fenestrations or openings in the upper surface of the tube cause trauma to the trachea, as well, because of the sharp edges created by probing the fenestration.
The inflation tube used for inflating the cuff is sometimes mounted in a groove in the cannula. Alternatively, the inflation tube takes the form of a secondary liner externally mounted on the cannula. These additional features also tend to cause trauma to the patient during the insertion and/or manipulation of the tracheostomy tube.
Consequently, improvements in the fabrication and the structure of the tracheostomy tube, in general, are desirable.